In this work, the annihilation mechanism of stacking faults (SFs) in epitaxial 3C-SiC layers grown on Si(001) substrates is studied by molecular dynamics (MD) simulations. The evolution of SFs ...located in the crossing (1&cmb.macr;11) and (11&cmb.macr;1) glide planes is considered. This evolution is determined by the interaction of 30° leading partial dislocations (PDs) limiting the stacking faults under the slightly compressive (∼0.45%) strain condition during the 3C-SiC layer growth. It is characterized in key terms: the distance between the PDs and the mutual orientation of their Burgers vectors. Two SF annihilation scenarios are revealed. In the first scenario, two PDs with opposite screw components of Burgers vectors, leading the SFs located in the (1&cmb.macr;11) and (11&cmb.macr;1) planes, are close enough (∼15 nm or less) and attract each other. As a result, the propagation of both SFs is suppressed
via
the formation of a Lomer-Cottrell lock at their intersection. In the second scenario, two PDs are far away one from the other (beyond ∼15 nm) and do not interact, or they repulse each other having equal screw components of their Burgers vectors. In this case, the propagation of only one of the SFs is suppressed. Obtained results explain the mechanism of SF annihilation and formation of SF intersection patterns experimentally observed by TEM investigations. They will provide important implications for the elaboration of advanced methods for the reduction of SF concentrations in epitaxial 3C-SiC layers on Si substrates.
Stacking fault annihilation mechanism in 3C-SiC epitaxially grown on Si(001) is studied by molecular dynamics simulations and its implications for improvement of 3C-SiC characteristics are provided.
Nanomedicine, or medicine using nanometric devices, has emerged in the past decade as an exhilarating domain that can help to solve a number of problems linked to unsatisfactory therapeutic responses ...of so-called ‘old drugs’. This dissatisfaction stems from inadequate biodistribution after a drug's application, which leads to a limited therapeutic response but also to numerous side effects to healthy organs. The biodistribution of drugs encapsulated in a nanoobject that will act as a vector can be modified to tune its therapeutic efficacy. This review provides a general overview of existing colloidal nanovectors: liposomes, polymeric micelles, polymeric vesicles, polymeric nanoparticles (NPs), and dendrimers. We describe their characteristics, advantages and drawbacks, and discuss their use in the treatment of various diseases.
•We introduce different types of tangent cones for convex vector SIO problems.•We introduce and compare four constraint qualifications (CQs).•We characterize (weakly, properly) efficient solutions in ...terms of cones.•KKT results are provided.
Convex vector (or multi-objective) semi-infinite optimization deals with the simultaneous minimization of finitely many convex scalar functions subject to infinitely many convex constraints. This paper provides characterizations of the weakly efficient, efficient and properly efficient points in terms of cones involving the data and Karush–Kuhn–Tucker conditions. The latter characterizations rely on different local and global constraint qualifications. The results in this paper generalize those obtained by the same authors on linear vector semi-infinite optimization problems.
Donor-doped SrTiO3 ceramics are very promising n-type oxide thermoelectrics. We show that significant improvements in the thermoelectric power factor can be achieved by control of the nanostructure ...and microstructure. Using additions of B2O3 and ZrO2, high density, high quality Sr0.9Nd0.1TiO3 ceramics were synthesised by the mixed oxide route; samples were heat treated in a single step under reducing atmosphere at 1673 K. Synchrotron and electron diffraction studies revealed an I4/mcm tetragonal symmetry for all specimens. Microstructure development depended on the ZrO2 content; low level additions of ZrO2 (up to 0.3 wt%) led to a uniform grain size with transformation-induced sub-grain boundaries. HRTEM studies showed a high density of dislocations within the grains; the dislocations comprised (100) and (110) edge dislocations with Burger vectors of d(100) and d(110) respectively. Zr doping promoted atomic level homogenization and a uniform distribution of Nd and Sr in the lattice, inducing greatly enhanced carrier mobility. Transport property measurements showed a significant increase in the power factor, mainly resulting from the enhanced electrical conductivity while the Seebeck coefficients were unchanged. In optimised samples a power factor of 2.0 × 10−3 W m−1 K−2 was obtained at 500 K. This is an ∼30% improvement compared to the highest values reported for SrTiO3-based ceramics. The highest ZT value for Sr0.9Nd0.1TiO3 was 0.37 at 1015 K. This paper demonstrates the critical importance of controlling the structure at the atomic level and the effectiveness of minor dopants in enhancing the thermoelectric response.
Correlations between the structural properties and nonradiative recombination (NRR) behaviors of threading dislocations in freestanding hydride-vapor-phase-epitaxy (HVPE) GaN substrates were ...investigated using cathodoluminescence (CL), the etch pit method, transmission electron microscopy (TEM), and multiple-photon excitation photoluminescence (MPPL). A statistical analysis with a one-to-one comparison of 480 CL dark spots (prior to etching) with their corresponding etch pits shows that all dislocation types act as NRR centers with a strong correlation between the NRR rate at the dislocation cores and the pit size. Further TEM observations accurately determined the magnitude and direction of Burgers vectors for dislocations under each type of etch pit, which firmly links the NRR behaviors with the dislocation type. It is found that a dislocation pair composed of (
a
+
c
) and (−
a
+
c
) threading mixed-type dislocations (TMDs) is the strongest NRR center among the considered dislocation types. The pair runs along the
c
-axis with a stable distance of 42 nm between them. This is followed by other types of TMD pairs,
a
+
c
TMDs,
ma
+
nc
TMDs (
m
and
n
are integers,
m
> 1 or
n
> 1), 1
c
threading screw dislocations, and 1
a
threading edge dislocations in descending order of NRR rates. Three-dimensional (3D) dislocation images visualized by MPPL revealed that most of the dislocations are nearly parallel to the
c
-axis, while the
a
+
c
TMDs are susceptible to large tilting. MPPL also indicates that the
ma
+
nc
TMDs may result from several merging dislocations.
Nonradiative recombination behaviors of threading dislocations and their correlation with the dislocation types.
Bovine ephemeral fever (atau 3-day sickness) adalah penyakit demam akut pada sapi dan kerbau yang disebabkan oleh Ephemerovirus dari keluarga rhabdoviridae dan ditularkan oleh vektor arthropoda. ...Penyakit tersebut biasa terjadi di daerah tropis dan subtropis. Dalam banyak kasus, dampak utamanya adalah pada penurunan produktivitas, produksi susu, kondisi tubuh, gangguan reproduksi, dan periode pemulihan yang lama pada beberapa hewan. Gejala klinis bervariasi pada setiap individu hewan, tetapi pada umumnya diawali dengan demam yang bersifat bifasik melanjut menjadi polifasik. Mortalitas biasanya rendah, namun, peningkatan kasus berakibat fatal telah dilaporkan dalam beberapa wabah akhir-akhir ini. Penyakit ini tersebar luas diberbagai daerah di Indonesia. Secara umum tidak menimbulkan kerugian ekonomi yang besar, asalkan segera mendapatkan pertolongan medis yang memadai sehingga tidak terjadi komplikasi dengan penyakit lain. Tulisan ini bertujuan untuk mengulas penyebab, metode diagnosa, dan terapi yang dapat dilakukan untuk menanggulangi kejadian BEF.
Penelitian ini merupakan penelitian tindakan kelas yang bertujuan untuk mengetahui pengaruh pemahaman konsep vektor dari subjek terhadap kemampuan pemecahan masalah fisika mekanika. Penelitian ...dilaksanakan dalam dua siklus yang masing-masing siklus terdiri dari empat tahap penelitian, yaitu perencanaan, pelaksanaan, pengamatan, dan refleksi. Data penelitian dianalisis berdasarkan nilai n-gain dari pre-test dan post-test pada setiap siklus penelitian. Hasil penelitian menunjukkan peningkatan n-gain berkriteria tinggi pada siklus II sebesar 0,70. Kemampuan pemecahan masalah dominan pada indikator pengajuan argumentasi dengan nilai n-gain sebesar 0,73. Keterlaksanaan rencana kegiatan pembelajaran pada setiap siklus menunjukkan nilai reliabilitas di atas 80% dengan aktivitas mahasiswa dominan pada kegiatan mengerjakan LKM. Berdasarkan temuan penelitian ini disimpulkan bahwa pemahaman matematika vektor memberikan pengaruh positif terhadap kemampuan pemecahan masalah fisika mekanika.
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•The pDNA condensation ability of RALA and WRAP5 has been evaluated.•A design of experiments tool (DoE) was used to find the optimal formulations.•The buffer pH and N/P ratio were ...considered the DoE inputs.•Vector size, zeta potential and pDNA complexation capacity were DoE outputs.•The ideal vectors were revealed: a great contribution for progresses in cancer therapy.
The field of gene therapy still attracts great interest due to its potential therapeutic effect towards the most deadly diseases, such as cancer. For cancer gene therapy to be feasible and viable in a clinical setting, the design and development of a suitable gene delivery system is imperative. Peptide based vectors, in particular, reveal to be promising for therapeutic gene release. Following this, two different peptides, RALA and WRAP5, have been investigated mainly regarding their ability to form complexes with a p53 encoding plasmid (pDNA) with suitable properties for gene delivery. To address this issue, and after an initial screening study focused on the dependence of pDNA complexation capacity with the nitrogen to phosphate groups (N/P) ratio, a design of experiments (DoE) tool has been employed. For each peptide/pDNA system, parameters such as, the buffer pH and the N/P ratio were considered the DoE inputs and the vector size, zeta potential and pDNA complexation capacity (CC) were monitored as DoE outputs. The main goal was to find the optimal experimental conditions to minimize particle sizes, as well as, to maximize the positive surface charges of the formulated nanosystems and maximize the pDNA CC. Through the DoE method applied, the optimal RALA/pDNA and WRAP5/pDNA formulations were revealed and show interesting features related to peptide structure and pDNA complexation ability. This work illustrates the great utility of experimental design tools in optimizing the formulation of peptide/pDNA vectors in a minimum number of experiments providing relevant knowledge for the development of more suitable and efficient gene delivery systems. The new insights achieved on these carriers clearly instigate deeper research on gene therapy.
The dislocation structure of single-crystalline germanium crystals grown by the Czochralski method in 2 1 1 and 1 1 0 directions has been examined by white beam X-ray topography. The dislocation ...densities in different parts of the crystals ranged from around 40 to 4000 cm
−2
. It was demonstrated that utilizing a well-executed Dash necking procedure with high growth speeds in growth directions parallel to a dislocation glide plane leads to the selection of dislocation line and type. Dislocations in the 2 1 1 crystal were mainly oriented in the 1 0 1 and 1 1 0 directions and hence confined within the (1&cmb.macr; 1 1) glide plane. A comprehensive Burgers vector analysis revealed that they were predominantly screw dislocations. The dislocation lines in the 1 1 0 crystal were mostly aligned to the 0 1 1&cmb.macr;, 1 0 1&cmb.macr;, and 1 0 1 orientations, within the (1&cmb.macr; 1 1) and (11&cmb.macr;1) glide planes and predominantly 60° dislocations.
X-ray topography of the 211 Ge crystal grown by the Cz-method shows that dislocations can be confined within the (1&cmb.macr;11) glide plane.
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